In FIGS. 1A-1C and, 2A-2C, there are illustrated in cross section two prior container caps in which an outer skin is secured to an inner core. In FIGS. 1A-1C, there is illustrated a bottle cap 100 with an unpainted, brushed, stainless steel skin secured to an inner plastic core. In FIGS. 2A-2C there is illustrated a bottle cap 200 with a painted stainless steel skin secured onto an inner plastic core.
In the bottle cap 100 of FIGS. 1A and 1B, an outer skin 102 of stainless steel is secured to an inner core 104 made of plastic, typically polypropylene. The inner core includes an inner cylindrical plug portion 106 concentrically surrounded by an outer tubular flange portion 108 that serves as a nut portion. An interior surface of the outer flange portion 108 is spaced from an exterior surface of the plug portion 106 and includes a molded threading 110 for mating engagement with a threading on a container neck (not illustrated). The outer flange portion 108 extends downwardly from a bight 112 at a top end of the inner cylindrical portion 106 to an edge portion 114. The edge portion 114 includes an edge face 116 facing away from the bight 112.
The outer skin 102 includes a top dome-shaped portion 120 with elongate dimples or depressions 122 and a downwardly extending tubular skirt portion 124. The outer skin defines an interior cavity with a cylindrical space 126 within the downwardly extending skirt portion 124 and a dome shaped space 128 within the dome-shaped portion 120.
During assembly, the inner core 104 is relatively inserted into the interior cavity defined by the outer skin 102 until the bight 112 bottoms out on an inner surface 130 of the dome shaped portion 120. Then, an edge portion or lip 132 of the outer skin 102 is partially rolled inwardly over the edge face 116 of the edge portion 114 into an L-shape in cross section to secure the outer skin 102 relative to the inner core 104.
One disadvantage of such an assembly is that painting of the outer skin 102 is not practical. First, the step of inwardly rolling the edge portion 132 of a pre-painted skin damages the paint by scratching it or otherwise causing it to crack. Second, post-assembly painting of the skin generally is not viable because the suitable paints require curing by baking at temperatures that exceed the melt temperature of the polypropylene plastic of the inner core 104.
In the bottle cap 200 of FIGS. 2A and 2B, an outer skin 202 of painted stainless steel also is secured to an inner core 204 also made of plastic, typically polypropylene. The inner core 204 similarly includes an inner cylindrical plug portion 206 concentrically surrounded by an outer tubular flange portion 208 that serves as a nut portion. An interior surface of the outer flange portion 208 is spaced from an exterior surface of the plug portion 206 and includes a molded threading for mating engagement with a threading on a container neck (not illustrated). The outer flange portion 208 extends downwardly from a bight 212 at a top end of the inner cylindrical portion 206 to an edge portion 214. The edge portion 214 includes an edge face 216 facing away from the bight 212.
Like the cap 100, the outer skin 202 of the cap 200 includes a top dome-shaped portion 220 with elongate dimples or depressions 222 and a downwardly extending tubular skirt portion 224. The outer skin defines an interior cavity with a cylindrical space 226 within the downwardly extending tubular skirt portion 224 and a dome shaped spaced 228 within the dome-shaped portion 220.
Unlike the stainless steel skin 102, the stainless steel skin 202 is painted and cured before assembly. Thus, there is no need to subject the skin to curing temperatures above the melting temperature of the polypropylene inner core 104 after assembly.
Also unlike the cap 100, to avoid the need to roll a bottom edge of the outer skin cylindrical skirt to secure the outer skin 202 to the inner core 204, the outer flange portion 208 of the inner core 204 includes an exterior circumferential concavity 240 positioned approximately midway between the bight 212 and the edge face 216. The circumferential concavity 240 provides a snap groove. The outer flange portion 208 also includes a bezel or ledge 242 that extends radially outward from the edge portion 214.
As can be seen, outer skin cylindrical skirt 224 includes an interior circumferential convexity 250 that matingly engages the circumferential concavity/snap groove 240. The convexity 250 is positioned approximately midway along the skirt 224. Due to the way in which the convexity is created, a circumferential concavity is formed about an exterior of the skirt 224.
During assembly of the cap 200, inner core 204 is relatively inserted into the interior cavity 226 defined by the outer skin 202 until the inner circumferential convexity 250 engages into the outer circumferential concavity 240 and snaps into place to secure the outer skin 202 to the inner core 204. At the same time, a bottom edge face or rim 252 of the outer skin tubular skirt 224 rests against the ledge 242 to hide the bottom edge face or rim 252, and avoid hazards from contact with a sharp edge that results from a trimming process.
Further, to assure engagement of the inner circumferential convexity 240 and the outer circumferential concavity 250, the outer skin tubular skirt 224 has a height dimension as measured from the ledge 242 that is longer than that of the flange 218, i.e., a longer dimension along a longitudinal axis of the cap 202. As a result, the point where the top dome-shaped portion 220 and the skirt 224 join is higher than the bight 212. Therefore, the bight 212 does not engage against the inner surface 230 of the dome portion, leaving excess interior space. This excess space increases the height of such caps and causes the caps to appear taller than the non-painted, brushed stainless steel caps.